The Facebook ad has been banned from appearing again in its current form

The post contained a video including the voice-over: “Having driven petrol-guzzling cars before, I realised that it is now time to switch to an electric car.

“With zero emissions, the i3 really is a clean car and helps to give back to the environment.”

Responding to a complaint that the claims were misleading, BMW said the i3 came in one model which was a battery electric vehicle with an optional “range extender” – a small petrol engine that did not power the car but maintained the battery charge.

The German manufacturer said the reason they had not qualified the zero-emissions claim by making it clear that it referred to driving the car was because the comment was made in an unedited testimonial.

The company said the i3 electric car produced no emissions when driving, unlike comparable petrol-fuelled cars, and it would therefore have been able to advertise it as “green”, which it considered comparable to “clean”.

It claimed that the car was advertised as “giving back to the environment” because it was being compared to the environmental footprint of a petrol car, not compared with driving no car at all.

The Advertising Standards Authority said consumers would interpret the ad to mean that the i3 had zero emissions and was a clean-energy car.

The Authority also said consumers would think that owning and driving the car had an overall benefit on the environment over its full life cycle, which it ruled was misleading.

The ASA said in a statement: “Because cars which used petrol cannot be described as ‘zero emissions’ or as a ‘clean car’ and it was not clear from the ad that the claim was in relation to the electric battery model only, we concluded that the claims were misleading.

“We told BMW to ensure that in future they made clear their environmental claims related to the all-electric vehicles only and not to make environmental claims about their products unless they held sufficient substantiation.”